sd_bus_path_encode(3) — Linux manual page


SD_BUS_PATH_ENCODE(3)      sd_bus_path_encode      SD_BUS_PATH_ENCODE(3)

NAME         top

       sd_bus_path_encode, sd_bus_path_encode_many, sd_bus_path_decode,
       sd_bus_path_decode_many - Convert an external identifier into an
       object path and back

SYNOPSIS         top

       #include <systemd/sd-bus.h>

       int sd_bus_path_encode(const char *prefix,
                              const char *external_id, char **ret_path);

       int sd_bus_path_encode_many(char **out,
                                   const char *path_template, ...);

       int sd_bus_path_decode(const char *path, const char *prefix,
                              char **ret_external_id);

       int sd_bus_path_decode_many(const char *path,
                                   const char *path_template, ...);

DESCRIPTION         top

       sd_bus_path_encode() and sd_bus_path_decode() convert external
       identifier strings into object paths and back. These functions
       are useful to map application-specific string identifiers of any
       kind into bus object paths in a simple, reversible and safe way.

       sd_bus_path_encode() takes a bus path prefix and an external
       identifier string as arguments, plus a place to store the
       returned bus path string. The bus path prefix must be a valid bus
       path, starting with a slash "/", and not ending in one. The
       external identifier string may be in any format, may be the empty
       string, and has no restrictions on the charset — however, it must
       always be NUL-terminated. The returned string will be the
       concatenation of the bus path prefix plus an escaped version of
       the external identifier string. This operation may be reversed
       with sd_bus_path_decode(). It is recommended to only use external
       identifiers that generally require little escaping to be turned
       into valid bus path identifiers (for example, by sticking to a
       7-bit ASCII character set), in order to ensure the resulting bus
       path is still short and easily processed.

       sd_bus_path_decode() reverses the operation of
       sd_bus_path_encode() and thus regenerates an external identifier
       string from a bus path. It takes a bus path and a prefix string,
       plus a place to store the returned external identifier string. If
       the bus path does not start with the specified prefix, 0 is
       returned and the returned string is set to NULL. Otherwise, the
       string following the prefix is unescaped and returned in the
       external identifier string.

       The escaping used will replace all characters which are invalid
       in a bus object path by "_", followed by a hexadecimal value. As
       a special case, the empty string will be replaced by a lone "_".

       sd_bus_path_encode_many() works like its counterpart
       sd_bus_path_encode(), but takes a path template as argument and
       encodes multiple labels according to its embedded directives. For
       each "%" character found in the template, the caller must provide
       a string via varargs, which will be encoded and embedded at the
       position of the "%" character. Any other character in the
       template is copied verbatim into the encoded path.

       sd_bus_path_decode_many() does the reverse of
       sd_bus_path_encode_many(). It decodes the passed object path
       according to the given path template. For each "%" character in
       the template, the caller must provide an output storage ("char
       **") via varargs. The decoded label will be stored there. Each
       "%" character will only match the current label. It will never
       match across labels. Furthermore, only a single directive is
       allowed per label. If NULL is passed as output storage, the label
       is verified but not returned to the caller.

RETURN VALUE         top

       On success, sd_bus_path_encode() returns positive or 0, and a
       valid bus path in the return argument. On success,
       sd_bus_path_decode() returns a positive value if the prefixed
       matched, or 0 if it did not. If the prefix matched, the external
       identifier is returned in the return parameter. If it did not
       match, NULL is returned in the return parameter. On failure, a
       negative errno-style error number is returned by either function.
       The returned strings must be free(3)'d by the caller.

NOTES         top

       Functions described here are available as a shared library, which
       can be compiled against and linked to with the
       libsystemd pkg-config(1) file.

       The code described here uses getenv(3), which is declared to be
       not multi-thread-safe. This means that the code calling the
       functions described here must not call setenv(3) from a parallel
       thread. It is recommended to only do calls to setenv() from an
       early phase of the program when no other threads have been

HISTORY         top

       sd_bus_path_encode() and sd_bus_path_decode() were added in
       version 211.

       sd_bus_path_encode_many() and sd_bus_path_decode_many() were
       added in version 227.

SEE ALSO         top

       systemd(1), sd-bus(3), free(3)

COLOPHON         top

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       manager) project.  Information about the project can be found at
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       This page was obtained from the project's upstream Git repository
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systemd 257~devel                                  SD_BUS_PATH_ENCODE(3)

Pages that refer to this page: sd-bus(3)sd_bus_message_new_method_call(3)systemd.directives(7)systemd.index(7)